The surface cyclic AMP receptors, cAR1, cAR2, and cAR3, promote Ca2+ influx in dictyostelium discoideum by a Gα2-independent mechanism

Jacqueline L. Milne, Peter N. Devreotes

Research output: Contribution to journalArticle

Abstract

Activation of surface folate receptors or cyclic AMP (cAMP) receptor (cAR) 1 in Dictyostelium triggers within 5-10 s an influx of extracellular Ca2+ that continues for 20 s. To further characterize the receptor-mediated Ca2+ entry, we analyzed 45Ca2+ uptake in amoebas overexpressing cAR2 or cAR3, cARs present during multicellular development. Both receptors induced a cAMP-dependent Ca2+ uptake that had comparable kinetics, ion selectivity, and inhibitor profiles as folate- and cAR1-mediated Ca2+ uptake. Analysis of mutants indicated that receptor-induced Ca2+ entry does not require G protein α subunits Gα1, Gα2, Gα3, Gα4, Gα7, or Gα8. Overexpression of cAR1 or cAR3 in gα2 cells did not restore certain Gα2-dependent events, such as aggregation, or cAMP-mediated activation of adenylate and guanylate cyclases, but these strains displayed a cAMP-mediated Ca2+ influx with kinetics comparable to wild-type aggregation-competent cells. These results suggest that a plasma membrane-associated Ca2+ -influx system may be activated by at least four distinct chemoreceptors during Dictyostelium development and that the response may be independent of G proteins.

Original languageEnglish (US)
Pages (from-to)283-292
Number of pages10
JournalMolecular biology of the cell
Volume4
Issue number3
DOIs
StatePublished - Jan 1 1993

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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